1. Field of the Invention
The present invention relates to a conveyance vehicle system including an automated warehouse including an automated warehouse controller, and a conveyance vehicle to transfer an article between the automated warehouse and the conveyance vehicle.
2. Description of the Related Art
Conventionally, there is known a conveyance vehicle system including a round track, a plurality of stations disposed along a route of the round track, and a plurality of conveyance vehicles traveling in one direction along the round track so as to convey articles. Between the stations and the conveyance vehicles, loading (an article to the conveyance vehicle from the station) and retrieving (the article from the conveyance vehicle to the station) are performed.
On the other hand, as an example of the above-mentioned station, there is known a stocker for stocking front opening unified pods (FOUPs) in a semiconductor factory. The stocker is an automated warehouse including a plurality of racks and a stacker crane moving along the racks. In the stocker, for example, when loading is performed, a ceiling conveyance vehicle conveys the FOUP to a loading port, and then the stacker crane conveys the FOUP to a predetermined rack. When retrieving is performed, the stacker crane conveys the FOUP from a predetermined rack to a shipping port, and then the ceiling conveyance vehicle conveys the FOUP away from the shipping port.
There is also known an automated warehouse in which a prior conveyance command is generated in advance only for an urgent article, and the article placed on the loading port is conveyed directly to the shipping port (see, for example, JP-A-2005-162451).
In the rear side of the loading port of the stocker, there is disposed a crane port, and a loading conveyer is disposed between the loading port and the crane port. The ceiling conveyance vehicle places the FOUP onto the loading port, and then the loading conveyer conveys the FOUP to the crane port. Then, the crane conveys the FOUP to a predetermined rack. On the shipping port side, there is disposed a same structure as the loading port so that the opposite action is performed.
A control action when the article is conveyed to the stocker will now be described. When the FOUP is placed on the loading port, an ID reader reads ID information of the FOUP and transmits the information to a stocker controller. Then, based on the ID information, the stocker controller transmits the ID information to a physical distribution controller and inquires whether or not the FOUP is to be conveyed. Then, the physical distribution controller transmits a conveyance command to the stocker controller. The stocker controller receives the conveyance command and, thereafter, controls the loading conveyer to transfer the article from the loading port to the crane port, and further controls the stacker crane to transfer the article from the crane port to a rack.
On the other hand, when the loading of the article from the conveyance vehicle starts, continuous loading may be performed at the loading port. Therefore, the article loaded to the loading port is required to be promptly conveyed to a rack of the automated warehouse. However, in the present circumstances, it is difficult to improve throughput at the loading port, and an article placed at the loading port may remain there. In this case, the conveyance vehicle cannot load another article to the loading port. As a result, conveyance efficiency of the entire conveyance vehicle system is significantly decreased.